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Radial Velocity Studies of Close Binary Stars. IV.
Rucinski, Slavek M.; Lu, Wenxian; Ogłoza, Waldemar
Radial velocity measurements and sine-curve fits to the orbital velocity variations are presented for the fourth set of 10 close binary systems: 44 Boo, FI Boo, V2150 Cyg, V899 Her, EX Leo, VZ Lib, SW Lyn, V2377 Oph, Anon Psc (GSC 8-324), and HT Vir. All systems are double-lined spectroscopic binaries, with only two of them not being contact syste…
The Spatial Distribution of O-B5 Stars in the Solar Neighborhood as Measured by Hipparcos
Maíz-Apellániz, Jesús
We have developed a method to calculate the fundamental parameters of the vertical structure of the Galaxy in the solar neighborhood from trigonometric parallaxes alone. The method takes into account Lutz-Kelker-type biases in a self-consistent way and has been applied to a sample of O-B5 stars obtained from the Hipparcos catalog. We find that the…
Radial Velocity Studies of Close Binary Stars. V.
Rucinski, Slavek M.; Lu, Wenxian; Mochnacki, Stefan W. +2 more
Radial velocity measurements and sine-curve fits to the orbital velocity variations are presented for the fifth set of 10 close binary systems: V376 And, EL Aqr, EF Boo, DN Cam, FN Cam, V776 Cas, SX Crv, V351 Peg, EQ Tau, and KZ Vir. All systems are double-lined, spectroscopic contact binaries (KZ Vir may be a low-inclination, close, noncontact bi…
Speckle Interferometry of New and Problem Hipparcos Binaries. II. Observations Obtained in 1998-1999 from McDonald Observatory
Mason, Brian D.; Hartkopf, William I.; Holdenried, Ellis R. +1 more
The Hipparcos satellite made measurements of over 9734 known double stars, 3406 new double stars, and 11,687 unresolved but possible double stars. The high angular resolution afforded by speckle interferometry makes it an efficient means to confirm these systems from the ground, which were first discovered from space. Because of its coverage of a …
Star Formation History in the Solar Vicinity
Bertelli, G.; Nasi, E.
The star formation history in the solar neighborhood is inferred by comparing a sample of field stars from the Hipparcos catalog with synthetic color-magnitude diagrams. We consider separately the main sequence and the red giant region of the H-R diagram. The criteria for our best solutions are based on the χ2 minimization of star distr…
Positions for the Outer Planets and Many of Their Satellites. V. FASTT Observations Taken in 2000-2001
Stone, Ronald C.
As part of an ongoing observing program with the Flagstaff Astrometric Scanning Transit Telescope (FASTT), this paper presents 1084 new equatorial positions taken in 2000-2001 for the outer planets Uranus, Neptune, and Pluto, as well as for 17 satellites of Jupiter-Neptune. All the positions were determined using differential reductions with refer…
Multiplicity of X-Ray-selected T Tauri Stars in Chamaeleon
Köhler, Rainer
We report on a multiplicity survey of a sample of X-ray-selected young stars in the Chamaeleon association. We used speckle interferometry and direct imaging to find companions in the separation range 0.13"-6". After correction for chance alignment with background stars, we find a multiplicity (number of binaries or multiples divided by number of …
Deep Hubble Space Telescope WFPC2 Photometry of M31's Thick Disk (?)
Sarajedini, Ata; Van Duyne, Jeffrey
We present deep color-magnitude diagrams (CMDs) for a field along the outer disk of M31 based on archival Hubble Space Telescope Wide Field Planetary Camera 2 observations in the F555W (~V) and F814W (~I) filters. The CMDs, which contain a total of about 50,000 stars, feature a prominent red giant branch (RGB) along with a significant population o…
CCD Speckle Observations of Binary Stars from the Southern Hemisphere. III. Differential Photometry
Franz, Otto G.; Horch, Elliott; Ninkov, Zoran
Two hundred seventy-two magnitude difference measures of 135 double star systems are presented. The results are derived from speckle observations using the Bessel V and R passbands and a fast readout CCD camera. Observations were taken at two 60 cm telescopes, namely the Helen Sawyer Hogg Telescope, formerly at Las Campanas, Chile, and the Lowell-…
WIYN Open Cluster Study. VII. NGC 2451A and the Hipparcos Distance Scale
Deliyannis, Constantine P.; Kozhurina-Platais, Vera; Girard, Terrence M. +5 more
We provide new evidence that NGC 2451A is undoubtedly a young open cluster, although sparsely populated. New cluster membership has been derived from relative proper motions of 5868 stars. In total, 136 stars down to V~15 have membership probability Pµ>=2%. New CCD BV photometry indicates that about 70 stars are indeed main-seq…